Process for the sulphonation of alpha nitro naphthalene



Patented Jan. 17, 1939 UNITED STATES PROCESS FOR THE SULPHONATION 0FALPHA NITRO NAPHTHALENE John M. Tinker, Perms Grove, N. J assignor to E.I. du Pont de Nemours & Company, Wilmington, Del., a corporati on ofDelaware No Drawing. Application July 26, 1937, Serial N0. 155,780

7 Claims.

The present invention relates to a process for the production ofnitro-naphthalene sulphonic acids. More particularly it relates to aprocess for the production of nitro-naphthalene sulphonic acids fromnitro-naphthalene. Still more particularly it relates to an improvedprocess for the production of 1-nitro-naphthalene-5-sul phonic acid from1-nitro-naphthalene.

Nitrc-naphthalene sulphonic acids have been produced in the prior art bythe sulphonation of l-nitro-naphthalene. Various sulphonating agentssuch as oleum, oleum plus sodium chloride, and chloro-sulphonic acidwere employed in this prior art process but it was found that manyunsatisfactory efiects resulted from their use. Thus, in the use ofoleum and in the use of chlorosulphonic acid the reaction was found tobe too vigorous, thereby resulting in charring, discoloration, and invery poor yields. Although the use of oleum plus sodium chloride gave asatisfactory yield there were still present other diificulties such asthe evolution of hydrogen chloride in large quantities which causedserious corrosion and also, the presence of a toxic condition whichcondition proved to be dangerous to the workers.

It is an object of the present invention to manufacturenitro-naphthalene sulphonic acids by a simple and efficient process. Afurther object is to manufacture nitro-naphthalene sulphonic acid fromnitro-naphthalene in the presence of a sulphonating agent. A stillfurther object is to manufacture 1-nitro=-naphtha1ene-5-sulphonic acidfrom l-nitro-naphthalene. A still further object is to overcome thedificulties which were encountered in the prior art processes of makingnitronaphthalene sulphonic acid. Additional objects will become apparentfrom a consideration of the following description and claims.

These objects are attained according to the herein described inventionwhich broadly comprises sulphonating a nitro-naphthalene in the presenceof a strong sulphonating agent and salt of a non-volatile acid. In amore restricted sense this invention comprises sulphonatingnitronaphthelene, in the presence of a strong sulphonating agent and asalt of sulphuric acid. The preferred embodiment of this inventioncomprises sulphonating l-nitro-naphthalene in the presence of oleum anda salt of sulphuric acid. Exceptionally good results have been obtainedby the use of sodium sulphate and for this reason, it is the preferredsalt.

This invention may be more readily understood by a consideration of thefollowing example.

Erample Heat a mixture of one thousand grams of 24% oleum, (76%H2SO4+24% free S03) 410 g. of an hydrous sodium sulphate and 500 g. of100% sulphuric acid to -50" C, and add during one hour, 500 g. ofl-nitro naphthalene. Heat the mass at -55 C. for 18 hours. Heat anotherhour at 85 0. Pour onto 10 liters of water, neutralize with lime andfilter. On evaporation of the water the nitro-naphthalene calciumsulphonates are obtained in a quantitative yield. On reduction of thecalcium or sodium salts of the mixed nitronaphthalene-sulphonic acidswith iron and acid, mixed naphthylamine sulphonic acids are obtainedfrom which of the theoretical yield of Laurents acid(l-naphthylamine-5-sulphonic acid) can be isolated by known methods.

It is seen from an examination of the above example that Laurents acidmay'be obtained by reducing with iron and sulphuric acid thenitronaphthalene sulphonic acid followed by extraction of the Laurentsacid from the iron sludge with sodium carbonate solution.

It is to be understood that the aforementioned example is representativeonly of the method of the practice of the invention. This method may besubjected to variation and modification. For instance in place of sodiumsulphate, referred to in the preceding example, or in admixturetherewith it is to be understood that salts of other nonvolatile acidsor other salts of sulphuric acid may be used. A few representativeexamples of materials falling within this category are sodiumbisulphate, ammonia salts of non-volatile acids, alkali metal andalkaline earth metal salts of non-volatile acids such as sulphuric,boric, phosphoric, naphthalene sulphonic, and the like. The alkali andalkaline earth sulphates and bisulphates generally as well as thesulphates and bisulphates of related metals have been found to giveexcellent results. As previously mentioned, these salts may be usedalone or in admixture with one another and when used in admixture withone another the proportions may vary widely without departing from thescope of this invention. However, it is to be understood that sodiumsulphate is the preferred salt for use herein.

The proportion of the salt to the sulphonating agent and the proportionof the sulphonating agent to the nitro-naphthalene may vary widelyWithout departing from the scope of this invention. However, thepreferred results have been obtained when the molar ratio of the salt tosulphur tri-oxide and of the sulphur tri-oxide to nitro-naphthalene hasbeen within the range of 1 to 3 moles of salt to 1 mole of sulphurtri-oxide and 1 to 3 moles of sulphur tri-oxide to 1 mole of nitronaphthalene.

It is preferred to use the aforementioned salts in the anhydrous formbecause an increased amount of oleum is required when the Wet salt isused. However, it is to be understood that the salt in the hydrated formmay be used without departing from the scope of tlr's invention.

The term oleum as used in the disclosure as well as the appendant claimsmeans sulphuric acid containing free sulphur tri-oxide.

By means of the present invention an entirely new class of salts areused in the production of nitro-naphthalene sulphonic acid. Due to thepresence of said salts in the sulphonation of nitronaphthalene it ispossible to produce nitro-naphthalene sulphonic acid by a process whichis superior and more economical than any heretofore known. Further, thedefects of vigorous reactions, charring, discoloration, poor yield,formation of hydrogen chloride, toxic condition, etc. are overcome by myherein disclosed invention.

As many apparently widely different embodiments of this invention may bemade without departing from the scope and spirit thereof, it is to beunderstood that the invention is not limited to the specific embodimentsthereof except as defined in the appended claims.

Having disclosed the present invention the following is claimed as newand useful:

1. A process which comprises sulphonating a nitro-naphthalene in thepresence of a mixture of a strong sulphonating agent and a salt ofsulphuric acid selected from the class consisting of alkali metal,alkaline earth metal, and ammonium salts.

2. A process which comprises sulphonating a Intro-naphthalene in thepresence of a mixture of oleum and a salt of sulphuric acid selectedfrom the class consisting of alkali metal, alkaline earth metal, andammonium salts.

3. A process which comprises sulphonating a nitro-naphthalene in thepresence of a mixture of oleum and sodium sulphate.

4. A process which comprises sulphonating lnitro-naphthalene in thepresence of a mixture of oleum and sodium sulphate.

5. A process which comprises sulphonating a nitro-naphthalene in thepresence of a mixture of a strong srulphonating agent and salt of anonvolatile acid selected from the class consisting of alkali metal,alkaline earth metal, and ammonium salts of sulphuric, boric, phosphoricand sulphonic acids.

6. A process which comprises sulphonating nitro-naphthalene in thepresence of a mixture of oleum and sodium sulphate, in the absence ofany volatile acid, the molar ratio of the salt to sulphur tri-oxide andof the sulphur tri-oxide to nitronaphthalene being within the range of lto 3 moles of salt to 1 mole of sulphur tri-oxide and 1 to 3 moles ofsulphur tri-oxide to 1 mole of nitro-naphthalene.

'7. A process which comprises sulphonating 1- nitro-naphthalene in thepresence of a mixture of oleum and sodium sulphate, in the absence of avolatile acid, the molar ratio of the salt to sulphur tri-oxide and ofthe sulphur tri-oxide to nitronaphthalene being within the range of 1 to3 moles of salt to 1 mole of sulphur trioxide and 1 to 3 moles ofsulphur tri-oxide to 1 mole of nitro-naphthalene.

J OHN M. TINKER.

CERTIFICATE OF CORRECTION,

Patent No. 2,lh5,965c January 17, 19590 JOHN M. TINKER. I

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 1,second column, line 6, for "1 0- 50 C." read hO-Lfi C. and that the saidLetters Patent should be read with this correction therein that the samemay conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of February, A. D. 1959.

Henry Van Arsdale.

(Seal) Acting Commissioner of Patents.

